The space vector-valued Siegel modular forms $M_{j,k}(\Gamma_2)$ can be decomposed as \[ M_{j,k}(\Gamma_2)=S_{j,k}(\Gamma_2)\oplus N_{j,k}(\Gamma_2) \] where $S_{j,k}(\Gamma_2)$ denotes the subspace of cusp forms on $\Gamma_2$ and $N_{j,k}(\Gamma_2)$ denotes its orthogonal complement with respect to the Petersson inner product. The previous decomposition is stable under the Hecke operators. The subspace $N_{j,k}(\Gamma_2)$ can be in turn decomposed into a direct sum, again stable under the Hecke operators. : \[ N_{j,k}(\Gamma_2)=E_{j,k}(\Gamma_2)\oplus KE_{j,k}(\Gamma_2) \] where $E_{j,k}(\Gamma_2)$ denotes the subspace of Eisenstein series. while $KE_{j,k}(\Gamma_2)$ denotes the subspace of Klingen-Eisenstein series. For $k>4$ and $j>0$, the subspace $KE_{j,k}(\Gamma_2)$ is isomorphic to the space of cusp forms of weight $k+j$ on $\SL(2,\Z)$.

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- Last edited by Fabien Cléry on 2021-05-07 10:36:59

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- 2021-05-07 10:36:59 by Fabien Cléry
- 2021-05-07 10:34:41 by Fabien Cléry
- 2021-05-07 10:27:40 by Fabien Cléry
- 2021-05-07 10:27:02 by Fabien Cléry
- 2021-05-07 09:31:11 by Fabien Cléry
- 2021-05-07 04:49:18 by Fabien Cléry
- 2021-05-07 04:34:59 by Fabien Cléry
- 2021-05-07 03:52:25 by Fabien Cléry
- 2021-05-06 16:57:04 by Fabien Cléry

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